Posterior reversible encephalopathy syndrome (PRES) without radiological correlate : Is it possible?

Objective PRES is a clinico-radiological entity often characterized by headache, seizures, altered sensorium, impaired vision and mostly accompanied by hypertension. PRES is often diagnosed on neuroimaging showing posterior predominant vasogenic edema. We report a case of childhood PRES who did not have any PRES defined radiological correlate. Methods A 12-year-old boy, diagnosed case of Chronic myeloid leukemia developed accelerated hypertension over 24 hours in 10th week chemotherapy. The child slipped into progressive encephalopathy after an episode of Right focal seizure and right hemiparesis. Amongst the drugs as etiology of PRES, Dasitinib was exhibited four weeks back. The metabolic work-up including plasma ammonia was normal. EEG to rule out nonconvulsive status was non-contributory except generalised slowing. MRI Brain & MR venography did not have any pathognomonic features of PRES or cerebral venous thrombosis. Results Hypertension was controlled by titrating the anti-hypertensive over next 48 hours and neurologically child completely improved gradually including complete recovery of hemiparesis. Despite the absence of characteristic neuroimaging changes the diagnosis of PRES was made in view of the presence of neurological signs after ruling out other causes of encephalopathy with Dasitinib (underlying drug) as predisposing factor for PRES. Conclusion PRES can be also be diagnosed in the presence of normal brain imaging after ruling out alternative diagnosis. Our case highlights the need to keep PRES as a clinical differential even in absence of characteristic radiologic features. Atypical features of PRES may in future lead to adopt an alternative terminology to encompass myriad clinical presentations.
Keywords: Hypertensive encephalopathy, Posterior Reversible Encephalopathy Syndrome,Dasitinib, Chronic Myeloid Leukemia